Animal Classification

Monachus schauinslandi

Description

The ancient Hawaiian name was "llio holo I ka uaua" meaning "dog that runs in rough water."
The Hawaiian monk seal is one of the most endangered marine mammals in the world, and the
rarest seal or sea lion in US waters. Weighing between 375-450 pounds (170-205 kg) and 7-7.5 feet (2.1-2.3 m) in length, females are slightly larger than males. Pups are 35 pounds (16 kg) at birth and 3 feet (1 m) long. Silvery-grey colored backs with lighter creamy coloration on their underside; newborns are black. Additional light patches and red and green tinged coloration from attached algae are common. The back of the animals may become darker with age, especially in males. Monk seals are known to live between 25-30 years.

Range/Habitat

The Hawaiian monk seal's entire range is within U.S. waters. The majority
of monk seals live in six main breeding subpopulations in the Northwestern Hawaiian Islands
(NWHI) at:

Kure Atoll

Midway Islands

Pearl and Hermes Reef

Lisianski Island

Laysan Island

French Frigate Shoals

Monk seals live in warm subtropical waters and spend two-thirds of their time at sea. They use
waters surrounding atolls, islands, and areas farther offshore on reefs and submerged banks.
Monk seals are also found using deepwater coral beds as foraging habitat. When on land, monk
seals breed and haul-out on sand, corals, and volcanic rock. Sandy, protected beaches surrounded by shallow waters are preferred when pupping. Monk seals are often seen resting on beaches during the day.

Smaller breeding sub-populations also occur on Necker Island and Nihoa Island, and monk seals have been observed at Gardner Pinnacles and Maro Reef. Most of the population is within the Papahānaumokuākea Marine National Monument, designated in 2006. Monk seals are now also found on the main Hawaiian Islands (MHI) where births have occurred on many of the major
islands.

Mating/Breeding

Females generally mature at age 5-6 and it is unknown when
males mature. Monk seals are promiscuous and mate underwater. Given male-dominated sex
ratios at some breeding colonies, group mobbing of "estrus" females is known to occur,
sometimes causing serious injury or even death to the female.
The gestation period is 10-11 months. Birthing rates vary with a range of 30-70% of adult
females birthing in a given year. While most births occur in late March and early April, birthing
has been recorded year round. Newborns are black, and then molt near the end of their nursing
period.
Nursing occurs for about 39 days, during which time the mother fasts and remains on land. After
this period, the mother abandons her pup and returns to sea. Although they are generally solitary
animals, females have been observed fostering others' offspring.

Behavior

Monk seals are primarily benthic foragers, feeding on a variety of prey including
fish, cephalopods, and crustaceans. Their diet varies by location, sex, and age. Adults are
generally nocturnal hunters while juveniles spend more time hunting species that hide in the sand
or under rocks during the day. Monk seals generally hunt for food outside of the immediate
shoreline areas in waters 60-300 feet (18-90 m) deep. Monk seals are also known to forage
deeper than 1,000 feet (330 m), where they prey on eels and other benthic organisms. Tiger
sharks and Galapagos sharks prey on monk seals.

Status

Hunted to the brink of extinction in the late 19th century, Hawaiian monk seals have
been declining since modern surveying. The monk seal population is currently declining at 4%
annually and is estimated at fewer than 1,200 individuals. Biologists predict this number will dip
below 1,000 in the next 3-4 years, placing this species among the world's most endangered.
While the larger NWHI population is shrinking, the MHI population is growing, with a
population estimated at over 100 animals.

At The Marine Mammal Center

While outside of The Marine Mammal Center’s 600
mile rescue range in California, we still help provide care for Hawaiian monk seals through a partnership with
NOAA and the National Marine Fisheries Service due to their endangered population and need
for help. In September of 2014, The Marine Mammal Center opened a new state-of-the-art hospital for Hawaiian monk seals located at Kailua-Kona on the Big Island. Called Ke Kai Ola (The Healing Sea in Hawaiian), the new facility has already rescued, rehabilitated, and rehabilitated a number of Hawaiian monk seal pups.

Age Classes

Age Class

Male

Female

Pup

< 1 month

< 1 month

Weaner

1-12 months

1-12 months

Yearling

1-2 years

1-2 years

Juvenile

n/a (classified as subadults)

n/a (classified as subadults)

Subadult

2-3 years

2-3 years

Adult

3+ years

3+ years

Hawaiian Monk Seal

Learn more about the Hawaiian Monk Seal and the work being done at Ke Kai Ola to help save this critically endangered species.

Shop our online gift store and you can help us care for our Hawaiian monk seal patients!